ClimateTalk is an open communication standard networking protocol that provides a mechanism for communicating messages between multiple types of components in an HVAC system using a common messaging structure over a physical medium. It is promulgated and supported by the ClimateTalk alliance, which is formed by a consortium of vendors in the HVAC industry. The CT-485 specification defines the physical medium requirements (e.g., the network layer, datalink layer, and physical layer specifications) for a network over which application level messages using the ClimateTalk protocol can be sent between various networked devices. The ClimateTalk alliance has promulgated a CT-485 Serial Hardware Specification for implementing the ClimateTalk protocol over the CT-485 network. At present, the latest version promulgated by the ClimateTalk alliance is CT-485 Serial hardware specification version 1.1, which was released on Jun. 23, 2011, the disclosure of which is incorporated herein by reference.
In a zone control HVAC system, a zone control manager (hereinafter, “controller”) manages the heat/cool/fan demands from multiple thermostats which are each typically located in different zones (physical areas) of a residential or commercial structure. The controller responds to the demands from each of the multiple thermostats in the different zones by operating individual airflow damper(s) which typically interconnect a HVAC unit (e.g., a forced air furnace and/or air conditioning unit) to each zone. The controller further controls the HVAC unit to satisfy the specific demands received from the thermostats in each specific zone of the zone control system.
While the ClimateTalk protocol provides a number of advantages in an HVAC system, such as a measure of compatibility between various HVAC components manufactured by different vendors, ease of use via Plug and Play (PnP) capability, and the ability to service proportional demand (as opposed to the on/off binary operation of conventional analog 24v AC HVAC components), the ClimateTalk protocol includes limitations that can make it unsuitable for use in a zone control HVAC system. These limitations stem from requirements in the ClimateTalk protocol, which generally limit the number of particular types of devices that may communicate with a single unit in a given HVAC system. For example, the ClimateTalk protocol requirements presently allow for only one ClimateTalk compliant thermostat device to be included in a particular ClimateTalk HVAC system.
This requirement is an impediment to vendors who wish to provide customers with the advantages and convenience of using ClimateTalk compliant devices in a zoned HVAC system. This is because, as described above, a zoned HVAC system typically includes a distinct thermostat in each zone of the HVAC system. However, the ClimateTalk protocol, in its present state, precludes the usage of more than one ClimateTalk thermostat in a given HVAC system. Thus, systems and methods that allow use of ClimateTalk devices in an integrated zone control HVAC system without limiting the number and type of device are desirable.